Shaft-hub assembly and method of production thereof

ABSTRACT

The invention relates to a shaft and hub connection for securing bearings, in particular ball bearings ( 12 ), on a shaft ( 10 ). The proposal is made that the hub part ( 14 ) of the bearing ( 12 ) encompassing the shaft ( 10 ) have at least one axial surface ( 20 ), against which a projection ( 24, 30 ) rests, which is produced from the shaft ( 10 ) by means of plastic deformation and prevents an axial movement.

BACKGROUND OF THE INVENTION

The invention relates to a shaft and hub connection as well as a processfor producing such a connection. In a known shaft and hub connection, inorder to prevent axial displacements, the bearing is supported as a ruleagainst an axial stop. The axial stop can be embodied as a step on theshaft, but this requires a shaft with an enlarged diameter in relationto the hub internal diameter. Securing rings for axial support are alsoknown, which are held in a recess in the shaft. To this end is necessaryto provide the shaft with a narrow-tolerance recess and during assembly,to slide the split ring on and anchor it in the recess before thebearing is mounted. This type of retention is expensive and costly toassemble.

SUMMARY OF THE INVENTION

The shaft and hub connection according to the invention for securingbearings, has the advantage that after the bearing is slid on, apositive and frictional, non-positive retention can be affixed in asingle step. It is not necessary that the shaft be oversized in certainregions in the bearing. The projection produced by the plasticdeformation can be embodied so that on the one hand, it has an axialsurface component that rests against an axial surface of the bearinghub. On the other hand, the deformation produces a slight diameterincrease in the vicinity beneath the hub so that the fixing is alsoreinforced in the circumference direction. The otherwise required pressfit of the bearing hub on the shaft is thus produced simultaneously withthe axial retention. The otherwise conventional preparations, such as aroughening of the shaft in the vicinity of the bearing seat or areduction of the shaft diameter in front of the bearing seat, can beeliminated. Since the projection from the material of the shaft restsdirectly against the outside of the bearing, a play-free fastening andretention are achieved without having to comply with narrow tolerancesfor this purpose.

In order to keep the stress on the bearing low, it is advantageous ifthe projection only extends over a part of the circumference of theshaft. In the event of considerable axial pressure on the bearing, theprojection is preferably produced over the entire circumference of theshaft.

If the projection is produced by rolling, then in rests in a preciselyshaped manner against the axial surface of the hub part. Furthermore,the stress concentrations that occur to an increased degree in suchnarrowed regions are optimally counteracted by the rounded shape used inthe rolling.

A very reasonably priced production of the projections is achieved bymeans of caulking, wherein the caulking tool is pressed into the surfaceof the shaft in the region in front of the axial surface and is movedtoward the axial surface. This raises projections which can be producedin very short cycle times. This process is therefore particularly suitedfor mass-produced articles.

The process according to the invention for producing a shaft and hubconnection, with the features of the collateral claim permits a veryreasonably priced, easy-to-assemble manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

Two exemplary embodiments of the shaft and hub connection according tothe invention are shown in the drawings and will be explained in detailin the subsequent description.

FIG. 1 shows a sectional view of a first exemplary embodiment and

FIG. 2 shows a sectional view of a second exemplary embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a shaft 10 which supports a ball bearing 12. The ballbearing 12 has a hub part 14, an external ring 16, and a number of balls18. The balls 20 can be secured by means of a cage (not shown).

In the vicinity of an axial surface 20 of the hub part 14, a projection24 is formed out of the shaft surface 22. On the side of the projection24 opposite from the axial surface 20, a recess 26 is let into the shaftsurface 22. The recess 24, which has been produced by means of plasticdeformation of the shaft surface 22, directly adjoins the axial surface20.

The projection 24 has the shape of an annular bead, which has beenproduced by means of a rolling tool 28 by pressing the material out fromthe recess 26. The projection 24 extends over the entire circumferenceof the shaft and thus permits a uniform support even under high stress.

In the exemplary embodiment, the rolling tool 28 is guided at an angle αin relation to the axial surface 20 and at a distance a, whichcorresponds to the thickness of the projection. An angle α in the rangefrom 0° to 45°, in particular of 15° has proven favorable for an optimalproduction of the projection. However it is also possible after theradial compression and rolling, to press the tool in the direction ofthe axial surface 20 so that the collar produced rests against thisaxial surface 20 without a gap. The distance a advantageously lies inthe range from 0.5 mm to 1.5 mm, particularly 1 mm.

FIG. 2 shows a second exemplary embodiment in which the same parts areprovided with the same reference numerals of the first exemplaryembodiment. In the vicinity of the axial surface 20 there, a projection30 is formed by way of the shaft surface 22. On the side of theprojection 30 opposite from the axial surface 20, a recess is let intothe shaft surface 22. The projection 30 is thus raised during theproduction of the recess by means of pressing a caulking tool 34 intothe shaft surface 22. The projection 30 rests against the axial surface20 in a frictional, non-positive manner and in a positive manner duringthis procedure.

By means of the plastic deformation of the shaft 10 in the region nextto the hub part 14, in both exemplary embodiments, the material of theshaft 10 is also expanded inside the hub part internal diameter D atleast in the vicinity of the axial surface 14. As a result, anadditional press fit is produced in this vicinity, which counteracts arotation of the hub part 14 on the shaft 10.

In a preferable process for producing a shaft and hub connection with aretention, the ball bearing 12 is slid onto the shaft 10 and fixed inthe vicinity to be fastened. Then, the projection 24 or 30 is formedwith a rolling tool 28 or a caulking tool 34 so that through plasticdeformation, the material rests as a projection against the axialsurface 20 of the hub part 14.

Is not necessary that the projection 24 produced by means of rollingextend over the entire circumference of the shaft 12. On the other hand,with a corresponding embodiment of the caulking tool 34, it can alsoproduce a complete annular bead.

What is claimed is:
 1. A process for producing a shaft and hubconnection for securing ball bearings on a shaft whereby after mountingof the ball bearing onto the shaft, a projection is produced by means ofa plastic deformation of the shaft surface by means of rolling anannular groove immediately in front of the projection whereby a rollingtool is guided at an angle of more than it, 0 degree to 45 degree, inrelation to the perpendicular of the shaft, so that the projection restsagainst an axial surface of the ball bearing hub and prevents an axialmovement.
 2. A process as defined in claim 1, wherein the rolling toolis guided at an angle of 15 degree.
 3. A process as defined in claim 1,wherein the rolling tool is guided in relation to the axial surface at adistance which lies in the range from 0.5 mm to 1.5 mm.
 4. A process asdefined in claim 3, wherein the rolling tool is guided in relation tothe axial surface at a distance which is equal to 1 mm.
 5. A process forproducing a shaft and hub connection for securing ball bearings on ashaft whereby after the mounting of the ball bearing onto the shaft, aprojection is produced by means of a plastic, deformation of the shaftsurface in a radial direction by a rolling tool, which is furtherpressed in the direction of the axial surface of the hub so that acollar is produced which rests against this axial surface without a gap.6. A process as defined in claim 5, wherein the rolling tool is guidedin relation to the axial surface at a distance which lies in the rangefrom 0.5 mm to 1.5 mm.
 7. A process as defined in claim 6, wherein therolling tool is guided in relation to the axial surface at a distancewhich is equal to 1 mm.